Underground cable



(No'Model.)

W. & T. G. MGMAHON.

l UNDERGROUND CABLE. No. 278,869. Patented Mar.13,1883.

N4 PETERS. Phem-Lnhngmpnw, wmmmm. u t;

UNITED STATES PATENT OFFICE.

WILLIAM MCMAHON AND TIMOTI-IltT G. llIoMAHON, OF CHARLESTOWN, NEWv HAMPSHIRE, ASSIGNORS, BY MESNE ASSIGNMENTS, TO THE UNDER- GROUND ELECTRIC CABLE COMPANY, OF NEW HAMPSHIRE.

UNDERGROUND CABLE.

SPECIFICATION forming part of Letters Patent No. 273,869, dated March 13, 1888.

Application tiled September 22, 1862. (No model.)

To all rhein 'it muy concern.:

3e it known that we, WILLIAM MchiAnoN and TIMOTHY G. MoMAHoN, both of Charlesy town, in thc county ot' Sullivan and State ot' New Hampshire, have invented certain new and useful Improvements in 'Underground Cables; and we do hereby declare that the following is a Iull, clear, and exact description of the same.

Io Our invention relates to insulated conductors for conveying electrical currents lI'or any of the purposes for which such currents are ordinarily used, and more especially to insulated underground conductors, although the I5 improvements are of utility in and applicable to any relations or positions in which insulated conductors of electricity are desirable.

In order to be commercially practicable, underground insulated conductors must be i'ur- 2o nished with an insulating and protecting mcdium economical in first cost, ol' high insulation, durable, and easy ofapplicatiomto which ends many materials', combinations, and .forms have been devised, the most common ci' which 2 5 have been compositions, solid or presumably solid at ordinary temperatures, but plastic at high temperatures, so that they could be applied to the conductors in a plastic condition. Some of these possessed the merit oi' economy 3o in first cost, but were found to lacl; durability, being aii'ected by thermal and hygromctric changes, and hence proved in the end to be lacking in actual economy. Others proved comparatively durable, and not subject to any great change under such influences; but their prime cost, due to expensiveness of the materials used,especially where rubber and such materials entered into-the composition, rendered them economically undesirable. In other 4o instances the conductors are placed and kept 5o used, the insulation itself was highly combustibio and proved in suine instances a source ot' great danger.

In view of these things the object of our invention is to produce an insulated conductor wherein the insulating material shall be cheap in prime cost, durable, ot' high insnlative capacity, easy of application, and, under ordinary circumstances, practically incombustiblc.

To accomplish this we'makc the insulation of the conductors as an already-termed tubeot 6o paper completely encircling, protecting, and insulating the conductor.

The insulating properties ol' paper were oi course known before our invention. For instance, in some positions, for small spaces or for temporary uses, sheetpaper has been wrapped around the conductor, and it has been suggested that paper-pulp be coated upon the conductor, but so far as we know no means were suggested or shown oi carrying this mere 7o suggestion into practice. Paper has also been used incidentally alternative with cloth or any other fabric as a base, upon which an asphaltV composition was applied, and a tube then formed thereof, which served as a mandrel, upon which a cement pipe was cast. Beyond this, so far as wc have been able to ascertain, no way has been devised or disclosed for utilizing the insulating properties of paper.

In our invention tubes are formed preferably Se from the pulp, and, when they are to be used in any peculiar situations, with any desired exterior con figuration best fitting them for use in 'the peculiar situation. They are formed under great pressure, so as to render them hard in substance, drm, and homogeneous, and. so formed they are practically incombustible, or at least not liable to combustion from any intluenceoi' the current. lVe prefer that the linsulating-tube should beloose upon or laround such pressure as will thoroughly consolidate it, rendering it hard, firm, and homogeneous. The Wire B is then passed therethrough or the tube slipped over thel con d uetor. The tube A is made in lengths or sections, and the various lengths or sections may be united by a male and female screw, s s', (see Fig. 5,) formed thereon or the adjacent ends ot' sections majv be beveled, (see o of, Fig. 6,) and thejoint protected by a thinible, T. Two or more aper tures, a a,1nay be made in the same tube, (see Fig. 2,) in each ot' which apertures is a wire, b b', which may lform a complete metallic eil-cuit or be members of independent electric circuits. For underground use a number 0f the insulating-tubes A or A may be placed in one protecting-envelope, C, Figs. 3 and 4;, which envelope C may be a wooden, iron, paper, or composition pipe, 0r which may be merely a box or trench.

By these means We are enabled to utilize the high insulating` properties of paper, and to furnish an insulated conductor, cheap, durable, easy of manipulation and use, and ot' high insulaiive capacity.

What We claim is- An insulated conductor for conveying electric currents, consisting of the combination of' a metallic conductor and a formed pipe otl paper only, substantially as set l'orth.

WILLIAH ,WIGMAHON TIMOTHY U. MCMAHON. Witnesses: I ll. W. PARKER, JOHN W. loLLiNsx 

